New cerium(IV)-substituted hydroxyapatite nanoparticles: Preparation and characterization

Hydroxyapatite and new cerium(IV)-substituted hydroxyapatite nanoparticles were synthesized by the co-precipitation method from aqueous solutions of various Ce/(Ce+Ca) atomic ratios ranging from 0 to 0.25. The structural properties of the hydroxyapatite powders were characterized by scanning electron microscopy (SEM) coupled with X-ray analysis (EDX), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) surface area analysis. The results confirm that cerium ions in the +4 as well as in the +3 states have been incorporated into the hydroxyapatite lattice. The (Ce+Ca)/P atomic ratio in the Ce-substituted hydroxyapatite samples was around 1.67. The prepared nanocrystalline powders consisted of hydroxyapatite as single crystallized phase with hexagonal structure and an average particle size of 20-60 nm. The antibacterial properties of cerium-substituted hydroxyapatite powders against Escherichia coli and Staphylococcus aureus bacteria were found to increase with increasing cerium content, being more effective against E. coli.